1. Field of the Invention
The present invention generally relates to semiconductor substrate processing systems and, more particularly, to plasma generation and control using a dual frequency RF source.
2. Description of the Related Art
Plasma enhanced semiconductor processing chambers are widely used to manufacture integrated circuit devices. In most plasma enhanced chambers, multiple radio frequency (RF) sources are utilized to form and control the plasma. For example, an RF source with a high frequency is typically used for plasma formation and ion dissociation. Additionally, an RF source with a lower frequency is often used to modulate the plasma sheath in order to control the accumulation of a DC voltage (i.e., bias voltage) on the substrate. The cost of the various sources and their related matching circuits are quite substantial and contribute to the high cost of the equipment needed to fabricate integrated circuits. Reducing the RF infrastructure without sacrificing any process benefit would result in significant cost savings.
Therefore, there is a need for an improved method and apparatus for plasma generation and control in a plasma enhanced semiconductor substrate processing.